Electric motor.



Patented 1an. 30, |990.

E.v .3. PLLSBURY.

ELECTRIC MOTOR.

(Application med Aug. 2S, 1899.)

(No Model.)

134: nonms Puras ca. Pug-rauwe.. wxsnmm UNITED STATES PATENT Orino,

EDWIN S. PILLSBURY, OF ST. LOUIS, MISSOURI.

ELECTRIC MOTOR.

SPECIFICATION forming part of Letters Patent No. 642,364, dated January 30, 1900.

Application led August 28, 1899. Serial No. 728.723. (No model.)

To colt wtont it' may concern:

Be it known that I, EDWIN S. PILLSBURY, a citizen of the United States, residing' at the city of St. Louis, State of Missouri, have in vented a certain new and useful Improvement in Electric Motors, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which itappertains to make and use the same, reference bein g had to the accompanying drawings, forming part of this specification.

Thisinvention relates to a new and useful improvement in electric motors of that type known as induction-motors, and is designed to be run by an alternating current of electricity. The structure shown in the drawings is especially adapted for use in connection with what is known as a ceiling-fan motor; but it is obvious that my invention can as well be used in connection with powermotors or motors other than the ceiling-fan type.

The objects of the invention are to simplify the construction of the motor, so that the same can be cheaply made, increase the efficiency of motors of this type, and at the same time enable the motor to be economically run.

With these objects in view the invention consists in the construction and arrangement of the frame and casing and its associate parts and in the novel winding of the field-magnets, all as will hereinafter be more fully described and afterward pointed out in the claims.

In the drawings, wherein like letters and numerals of reference refer to like parts Wherever they occur, Figure l is a vertical sectional View through my improved motor, and Fig. 2 is a partial top plan view of the same. Fig. 3 is an inverted plan view of the switch, taken on line 3 3, Fig. l.

A indicates a frame-plate provided on its upper face with a hollow boss, by which the same may be suspended from the ceiling by a pipe threaded thereinto. (Not shown.)

This frame-plate is provided with marginal flanges a, which receive the held-magnet core B, said core being clamped in position by a ring h, as shown in Fig. l.

C indicates a hollowT shaft iixed in the frameplate A, which hollow shaft receives the bellshaped oil-cup D in its lower end, whose hollow central projection is secured thereinto,as shown, said projection extending upwardly a considerable distance into the hollow shaft C.

E indicates the armature frame or spider, formed with a hub portion, through which passes the hollow shaft O, said hub portion of the armature-frame resting at its lower end on a ring F, between which and a correspondin g ring G are arranged a series of balls H, forming an antifriction -bearing for the rotating element of the machine. Under the ring G, I prefer to arrange a leather or other suitable flexible washer I, which rests upon a supportingring J, screwthreaded and clamped on the lower end of the hollow shaft O. The bell-shaped oil-cup D contains these rings and their associate parts, forming the antifriction-bearin g for the armature-hub, in addition to which a suitable quantity ,of oil is introduced, so that said bearing is practically submerged in oil at all times.

As the oil has a tendency to creep up between the armature-hub and the fixed shaft C, I arrange a reservoir or receiving-chamber e in the upper portion of the armature-hub formed by the over-hanging anges e', and in the event that oil reaches this chamber the same is conducted back to the oil-cup through suitable passage-ways c, formed in the armature-hub. This construction prevents the oil from being thrown from the rotating element by centrifugal force.

On the lower face of the armature-frame are provided sockets K for the reception and attachment of the. shanks of the fan-blades. Heretofore these sockets have been drilled or cored with circular openings to permit rotatory adjustment of the fan-blades therein, after which the blades were clamped in their adjusted positions by means of binding-screws k. In this construction I also employ setscrews; but in order to prevent the fan-blades from twisting in their sockets, as is their natural tendency in operation, I adjust the shanks in position so as to balance the armature, and then mark a line across their inner ends for the purpose of forming ashoulder or iiattening one side of the shank. I then introduce a block L in the bore of the socket and secure the same in position by a screwbolt Z or other suitable means, and when the fan-shank is introduced its flattened portion ICO registers with this block, and the block being fixed in place prevents the fan-blade from twistingafteroncebeingadjusted. Thebnding-screw 7c now acts merely to prevent longitudinal movement of the shank, all twisting strain being relieved therefrom by the block L.

The armaturefframe is formed with an upwardly-extending flange at 'its periphery, whose internal diameter is greater than the laminated core which it receives. This core I have marked M in the drawings, and in assembling the parts it is centered on a shoulder m, which is preferably turned down to true the same. The core is placed in position against this shoulder, and as the externaldiameter thereof is less than the internal diameter of the fiange said core may be adjusted laterally in order to make the same concentric, a suitable former or extending tool being used for the purpose. After the core is made concentric Babbitt metal m is poured between the core and armature-frame to fill the space and hold the core in position.

N indicates induced-current-conducting bars arranged transversely the inner face of the core, whose ends are preferably slotted to receive short-circuiting rings O, forming what is commonly known as a squirrel-cage armature. The concentric hollow projection of the bell-shaped oil-cup D has its bore in axial alinement with the bore of the hollow shaft O, and through these alining bores I introduce a switch-stem P, whose lower end is centered relative to the bore by means of suitable washers p, said lower end also carrying a butterfiy-head Q, by which the stem or rod may be rotated. The upper end of this rod P carries a switch-blade R, cooperating with suitable contacts secured to an insulationplate S, fixed in the hollow7 boss of the frame A and secured in position by suitable bolts, as shown. This insulation-plate is of such a size as to be introduced laterally into the boss, after which it is secured in position. The switch-blade likewise is introduced lat erally through an opening of this hollow boss, while the rod P is introduced from underneath and connected to the switch-blade by means of a threaded projection fr.

I will now describe the field-magnet windings. The laminated core B is formed with T-shaped polar projections, preferably radially arranged, the spaces between which receive the coils, said spaces opening to the exterior through a contracted mouth inthe periphery of the field. There are a sufficient number of these polar projections, and suitable windings are arranged thereon to produce a rotating field of such character that a starting torque is developed, which starting torque as the motor gets up speed may be reduced by cutting out certain of the windings on these polar projections.

In Fig. 2 I have shown the main coils as including five polar projections, alternate poles being wound in opposite directions, as shown. Vire l is wound a sufficient number of turns around the central polar projection and is then carried to include the next two adjacent polar projections, including three polar projections, where it is wound with a sufficient number of turns, after which it is extended farther to include the next two adjacent polar projections, making ve in all, Where it is wound a sufficient number of turns, completing the windings of the main coil. All the windings of each individual pole are in the same direction, while these main coils are wound in opposite directions on alternate polar projections. The main coils of each pole being wound as above described may be said to form substantially a pyramid whose apex is located about the center of said pole. The middle polar projection being surrounded by more turns than the adjacent projections, said turns preferably decreasing on each side of the center in about the same proportions until the eXtreme or end poles are reached, the pole so wound will generate magnetic lines of force corresponding to said windings*that is, the magnetism will be most intense at about the center of the pole, said magnetism decreasing as it approaches the ends thereof.

2 indicates a wire which is wound around a portion ot the polar projections of each pole in such manner that the greatest number of windings of wire 2 are around a polar projection to one side of the center of a pole included within the windings of the main coil. These windings of wire 2 I will term phase or starting coils, and in practice they are preferably high-resistance coils with a comparatively low reactance. These phase or starting coils, as shown in Fig. 2, consist of windings placed around a polar projection next adjacent the middle polar projection of a pole, which winding is then continued around the neXt adjacent polar projection, being the middle polar projection of the pole and the outer polar projection of thesame pole, said winding being wound in the same direction as the main coil and continuing in series to the next pole, where it is wound in the same direction as the main coil on that pole or in the opposite direction from the winding of the first pole described. These phase-coils are also preferably arranged in pyramidal7 form, as -it might be termedthat is, the magnetic lines of force they develop are most intense at about the middle thereof and decrease toward the ends. It is obvious, however, that instead of having these phase or starting coils wound in the same direction as the main coil of any given pole said phase or starting coils can be wound in an opposite direction to the main coil of a given pole, whereby a counter electromotive force would be set up in that pole to produce an asymmetric field; but it will be obvious that this counter electromotive force IOO IIO

or the neutralization of some of the magnetic lines of force of the main coil will render the motor less efficient in proportion to the counter electromotive force set up by this phase or starting coil. It is also obvious that in order to produce a iield of greater asymmetry two phase or starting coils can be arranged on the polar projections of a single pole, one of said coils being wound in the same direction as the main coil and the other in an opposite direction, so that when these coils are energized an asymmetric or rotating iield of magnetism will be produced. It will also be observed that these phase or starting coils can be short-circuited on themselves or otherwise, whereby the induced currents set up therein would produce a counter electrometive force sufficient to establish an asymmetric ield.

In the construction of a motor provided with phase or starting coils connected in series or designed to be short-circuited it is obvious that a switch may be employed to control these windings and also the main windings. I have not shown such a switch in the drawings; but its construction will be readily understood by those skilled in the art, it being of the ordinary kind and adapted in one position to cut in the main and starting coils, after which when the motor has attained speed the starting-coils may be cut out for the purpose of running the motor more eco.- nomically and at a lower speed.

The term phase or starting coils is used here for the purpose of distinguishing said coils from the main or primary coils. On account of thehigh resistance and low reactance of the phase or starting coils the polar projections around which they are wound are more sensitive or magnetism is more quickly induced therein than with the heavier winding of the main coils. The result of this is that" the magnetism produced by the main coils practically lags behind in phase in substantially the same way as if a two-phase current were employed, the starting-coils receiving one phase of the current and the main coils the other. I have therefore called these starting-coils phase-coils, although they do not respond strictly to the definition of that term.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is'- l. In an induction-motor, the combination with an armature, of a field-core provided with polar projections, main coils including a plurality of said polar projections to form the different poles, said coils being so arranged that the magnetic lines of force are most intense at about the center of each pole, and phase or starting coils which include a plurality of the polar projections of each pole, whereby, when said coils are energized, the phase or starting coils cause the center of magnetism to be laterally displaced to produce an asymmetric field; substantially as described.

2. In an induction-motor, the combination with an armature provided with short-circuited induced-current-conducting bars,ofaiieldcore provided with polar projections, main coils arranged substantially in pyramidal form which are wound around a plurality of said polar projections in the formation of the different poles of the field-magnet, phase or starting coils which are laterally displacedfrelative to the centers ofthe different field-poles, which phase or starting coils include a plurality of polar projections; substantially as described.

3. The combination with a field -magnet core provided with a plurality of polar projections, of main coils which include in their windings a number of said polar projections, said windings being so arranged that the central polar projection of each pole is surrounded by a greater number of turns than the polar projections of the same pole on each side thereof, alternate poles being wound with said main coils in opposite directions, and phase or starting `coils which include a plurality of polar projections of each pole; substantially as described.

4. The combination with a held-magnet core provided with polar projections, of main coils which include a plurality of said polar projections in the formation of each pole, and

high-resistance phase or starting coils laterally displaced relative to the center of each pole, said phase-coils including a plurality of polar projections in each pole; substantially as described.

5. The combination with a field-pole composed of a plurality of polar projections, of a main winding therein arranged substantially in pyramidal form, so as to make the magnetism of said pole most intense at about its middle, and a phase or starting coil arranged substantially in pyramidal form, and laterally displaced relative to the point of intense magnetism induced by the main winding; substantially as described.

6. In an induction-motor, the combination with an armature provided with short-circuited induced-current-conducting bars, of a field-core provided with polar projections, main coils including a plurality of said polar projections to form the different poles, said coils being so arranged that the magnetic lines of force are most intense at about the center of each pole, and phase or starting coils which are laterally displaced relative to the intense center of magnetism developed by the main coils; substantially as described.

In testimony whereof I hereunto affix my signature, in the presence of two witnesses, this 21st day of August, 1899.

EDWIN S. PILLSBURY.

Witnesses:

F. R. CORNWALL, RALPH KALISH.

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